Adhesive and method of making the same.



HAM and HENRY V. DUNHAM,

., UniTED STATES PATENT OFFICE.

ANDREW A. DUNHAM, F BAINBRIDGE, NEW YORK, AND HENEY V. DUNHAM, OE

VELASCO, TEXAS, ASSIGNORS TO CA BEIN COMPANY OF AMERICA, 91 NEW YOEK; N.Y., A CORPORATION OF NEW JERSEY.

ADHESIVE AND METHOD OF MAKING- THE SAME;

No Drawing.

Specification of Letters Patent. Application med m a, 1911. Serial no.scam.

Patented Feb. 18,1913.

To. all whom it may concern Be itcknown that we, ANDREW A.-DUN- citizensof the United States, residing in Bainbridge,

and Velasco, county of State of New York, Brazoria, State of Texas,respectively, have invented certain new and useful ImprovementsinAdhesives and Methods of Making the Same; and We do hereby declare thefollowing to be a full, clear, and exact descri tion of the invention,such as will enable ot iers skilled in the art to which it appertains tomake and use the same.

Our invention relates to certain new and useful improvements in thetreatment of starch to make it suitable for the coating of aper. It isbased upon the discovery that by the action of a suitable agent, such asoxalic acid, the starch can be appropriately modified, and themodification can be arrested at a stage which will adapt the resultingproduct for subsequent admixture with a suitable mineral base or fillerto produce a coating on paper which will be strongly adhesive to thepaper. p

In the preferred practice of our invention,

county of Chenango,

'we contemplate the manufacture of a substantially dry product suitablefor storage and transportation as an article of manufacture and sale;although, as will hereinafter more fully appear, the invention, broadlyconsidered, is of such a character that it may be practised, in thecoating of paper, without the production of an intermediate dry roduct.

In the preferred practice referred to, we first treat the starch Withoutbreaking up the starch granules and with the employment of the minimumamount of Water as the dissolving medium for the modifying agent, 2'. e.an amount sufficient to bring the modifying agent into intimate contactwith the individual starch granules throughout the mass; we then dry themass until it has been brought back to substantially the condition ofdryness of the original starch, which usually contains from 9% to 10% byweight of moisture. The drying operation is preferably conducted inoacuo and temperature insufiicient to break up the starch granules andthe modifying action of the acid is continued, under the stimulatingeffect of the existing temperature conditions prevailing in the vacuumdrier, until arrested at a stage corresponding to the viscositycontemplated for ultimate incorporation with the mineral base. In orderto thus arrest the modification and to positively insure against itsrecurrence in .the mass, we employ an alkaline re-agent of any suitablekind and which may be, for-instance, an alkali which when added to theacidulated modified starch will act as a neutralizing agent and will soadapt the product that, when added to the mineral base, as hereinafterdescribed, there will result no such thickening up of the same into apasty mass as would make it unsuitable for paper coating. On thecontrary, the roduct when thus added to the mineral ase, will runsmoothly when applied by the ordlnary coating machines well known to theart. We have found that ammonia possesses this property and wepreferably use the same, for the reason that the employment of ammoniapermits of the complete neutralization of the mass with the productionof a neutral salt and the volatilization of any excess of ammoniaemployed. To produce the dry product, the neutralized modified starchmay then be dried in any usual manner.

In order to more fully describe the details of a typical example of thepractice of our invention for the production of a dry product, we willnow give an instance of its commercial practice, under preferred.conditions: 800 lbs. of the starch are admixed with a solutionconsisting of 40 lbs. of oxalic acid crystals dissolved in 200 lbs. ofWater, and the mixture is stirred in an apparatus of the type of a doughmixer or the like until the solution has been uniformly andhomogeneously incorporated with the starch granules. At the conclusionof-the mixing operation, the starch mass will have absorbed the solutionof oxalic acid and will be sufliciently damp so that, if a portion of'itis squeezed in the hand, it will have sutlicient cohesion to barely ballor cake together, showing the imprint ofthe fingers. In some instances,a greater or a less amount of oxalic acid may be employed, but theamount of oxalic acid should preferably not fall below from 30 to 35lbs. in any case in a mixture of the relative quantities of starch andwater above noted. So also, a larger.

' facture.

oxalic acid, is next introduced into a rotaryv vacuum drier, which ispreferred for the reason that it insures the uniform conduct of theprocess'during this period, and particularly because it permits thespeeding up of the drying operation, at a temperature which is safelybelow the limits of the temperature which would break up the starchgranules and convert the mass Into a paste. The rotary vacuum drier thatwe prefer for the purpose would be provided with a steam jacket, whichmay conveniently be supplied with steam at say 20 lbs; superatmosphericpressure, corresponding to a temperature of about 259 F. Within thevacuum drier, we prefer to, maintain a vacuum of say 20 inches, so thatthe internal temperature, during the drying operation shall becorrespondingly restricted well below the limit of the breaking up ofthe starch granules. It

' is found that at the termination of a period varying somewhat with theprevailing conditions, but usually about one and-one half hours, andwhile the drier is rotating at an average speed of from five to sixrevolutions per minute, the water of solution has been practicallyexpelled, leaving the starch with about its original contentof-moisture, say from 9 to 11% by weight. Under the continued action ofthe heat, the oxalic acid exerts acontinued modifying action upon thestarch, and, at this stage of the operation, extreme care must be takento supervise and test itsprogress, so that it'may neither fall short ofnor' exceed the limits necessary for the ultimate result. To this end,from time to time, the rotation of thedrier is interrupted and a sampleof the contents is taken and quickly tested for viscosity. A suitableviscosity test which we have used with successful results consists incomparing a the rate 'of flow of a standardsolution of the test. sample,neutralized and boiled, as hereinafter specified, with the rate of flowof water through a burette, having a length of 3 6.inches and aninternal diameter of ,gths

of an inch and delivering 58 c. c'. of water in a period of half aminute. To 100 grams of thedry starch is first added 400 grams of coldwater. The water and starch are stirred well together and then is addedsufficient ammonia of 26 Baum to make the solution a-lkalin. The mixtureis then heatedto between 185 F. and 190 F. thereby breaking up thestarch granules. Then enough cold water is added to produce a volume ofabout 970 c. c. of the mixture at a temperature of 100 F. In themeantime, the burette has been brought to the same temperature and .ofwater.

stirred, so as to interrupt the modifying-acthe burette is filled'withthe solution and its rate of flow tested. When the test of any ruptedand its contents are immediately dis- 1 5 charged into a second mixingapparatus containing 40 lbs; of 26 ammon a in 200 lbs. The mass is atonce vigorous y tion by thoroughly neutralizing the acid. Thereupon, theneutralized mass of modified starch 1s dried in any convenient manneras,

for instance, by being placed in shallow trays and heatedin a dryingtunnel or the like. It will usually be found desirable, before placingthe neutralized mass in the trays to pass it through a breaker for thepurpose of breaking up any lumps that may have formed, so that thedrying operation may proceed with corresponding promptness anduniformity. It is unnecessary to take I special precautions during thedrying of the neutralized mass, inasmuch as there will be no prejudicialchanges in the desired characteristics of the modified starch after ithas reached this stage of the operation.

In order to make up the composition employed for the coating oflithographers paper, a' suitable mineral base may be em ployed, as, forinstance, kaolin, blanc fixe, satin white, etc. In the case of kaolin,100 lbs. may be employed intimately mixed with 50 lbs. of water. 25 lbs.of the dry modified starch produced in accordance with the methodhereinbefore described is then intimately mixed with 100 lbs. of coldwater and the mixture is heated to a temperature such that the starchgranules will be broken up, a temperature of about 185 F. to 190 F.ordinarily suflicing for the purpose. The starch product thus obtainedis then mixed with the kaolin and water until the whole is in ahomogeneous union. The mixture is then. strained and is ready for thepaper coater, who may use additional water for thinning down purposes,according to the particular character of coating which he wishes toproduce for the purpose at hand.

When, for special reasons, it is desired to make use of the fundamentalfeatures of our invention, for the production of a composition to beimmediately applied to the paper, we may proceed directly with theproduction of the coating without producing the modified starch in a drystate. In accordance with this practice, we prefer to introduce thestarch and the oxalic acid, in the same relative quantities in a volumeof water sufficient to bring the starch into suspension, and to thenheat the mixture sufliciently to break up the starch granules and fullaction of the oxalic acid. This is entirely feasible on an economicalbasis, for the reason that the mass thus produced does not require to bedried before being put into use; whereas, for the production of a dryproduct it is undesirable to thus break up the starch granules for thereason that the resulting paste would be difiicult to dry except atconsiderable expense, and under conditions diflicult to effectuallysupervise and determine.

When, in the modification of the process referred to, the boiling hasproceeded until a test sample, containing the same relative weight ofstarch to water as in the standard solution hereinbefore specifiedindicates the desired viscosity, the necessary amount of ammonia isadded to the vat to effect the, entire neutralization of the acid orlike modifying agent, and the resultant liquid solution of modifiedstarch is ready for immediate incorporation with the correspondingrelative quantity of mineral base for the final coating composition. Themineral base in admixture with the appropriate amount of water isthereupon immediately incorporated with the solution of modified starch,and the composition thus produced is ready after straining, for use asbefore.

In some instances, we prefer to add to the composition of modifiedstarch, a suitable amount of formaldehyde, to guard againstdecomposition and fermentative action, when, for any reason, such actionis to be apprehended, as, for example, when the exigencies ofmanufacture or use cause it to be kept temporarily (say over night) inthe wet or moist state.

Having thus described our invention, what we claim is: I

1. The method of producing an adhesive for use in paper coating, whichconsists in subjecting a body of starch to the action of oxalic acid andneutralizing it by, means of ammonia when it has been so far modifiedthat, thus neutralized, it will have, in admixture in Water with a largeproportion of a suitable mineral base, strong adhesion,and capability ofbeing applied as a'facing coating to paper; substantially as described;

2. The method of producing an adhesive for use in the coatingof paper,which consists' in subjecting starch to the action of oxalic acid insolution, evaporating the solvent and neutralizing the acid after it hasmodified the starch tosuch an extent that when subsequently dissolved\vitlrfrom four to five parts of water and mixed with a large proportionof a suitable mineral base, it will have strong adhesion and capabilityof being applied as a facing coating to paper; substantially asdescribed.

3. The method of producing an adhesive for use in the coating of paper,which consists in subjecting starch to the action of oxalic acid insolution, evaporating the solvent, arresting and neutralizing the actionof the oxalic acid by means of ammonia when the starch has been so farmodified that, thus neutralized, it will have, in admixture in waterwith a large proportion of a suitable mineral base, strong adhesion andcapability of being applied as a facing coating to paper, and drying themodified neutralized starch; substantially as described.

4. The method of producing an adhesive for use in the coating of paper,which consists in modifying starch by oxalic acid to such an extent thatwhen admixed with nine parts by weight of water, and neutralized withammonia and heated to a temperature sufficient to break up its starchgranules it will have, after cooling to 100 F. a viscosity ranging from40 c. c. to 45 c. c. per half minute as measured by a burette delivering58 c. c. of water per half minute, and then arrestin the modification byneutralization; su stantially as described.

5. As an adhesive, starch modified by oxalic acid and having themodification arrested at such a point that when admixed with water, witha large proportion of a suitable mineral base, it will be stronglyadhesive, and capable of being applied as a coating to paper;substantially as described.

6. As an adhesive, starch modified by oxalic acid to such an extent thatwhen admixed with nine partsby weight of water and neutralized withammonia and heated to a. temperature sufiicient to break up its starchgranules it will have, after cooling to 100 F., a viscosity ranging from40 c. c. to

45 c. e. per half minute as measured by a burette delivering 58 c. c. ofwater per half minute; substantially as described.

In testlmony whereof we aflix our signatures in the Presence of twowitnesses.

Witnesses:

WARD C. Looms, R. O. WILCQ".

